Abstract: The interface resistance between the source/drain and gate of an HFET may be significantly reduced by engineering the bandgap of the 2DEG outside a gate region such that the charge density is substantially increased. The resistance may be further reduced by using an n+GaN Cap layer over the channel layer and barrier layer such that a horizontal surface of the barrier layer beyond the gate region is covered by the n+GaN Cap layer. This technique is applicable to depletion and enhancement mode HFETs.

Abstract: A method of fabricating a GaN HEMT includes growing a first epitaxial layer on a substrate, growing a second epitaxial layer on the first epitaxial layer, growing a third epitaxial layer on the second epitaxial layer, depositing a first dielectric film on the third epitaxial layer, using dielectric films to form a first sidewall dielectric spacer, forming a sidewall gate adjacent the first sidewall dielectric spacer. The sidewall gate may be made to be less than 50 nm in length.

Abstract: The present invention relates to fabrication of enhancement mode and depletion mode High Electron Mobility Field Effect Transistors on the same die separated by as little as 10 nm. The fabrication method uses selective decomposition and selective regrowth of the Barrier layer and the Cap layer to engineer the bandgap of a region on a die to form an enhancement mode region. In these regions zero or more devices may be fabricated.

Abstract: A method for fabricating a gate structure for a field effect transistor having a buffer layer on a substrate, a channel layer and a barrier layer over the channel layer includes forming a gate of a first dielectric, forming first sidewalls of a second dielectric on either side and adjacent to the gate, selectively etching into the buffer layer to form a mesa for the field effect transistor, depositing a dielectric layer over the mesa, planarizing the dielectric layer over the mesa to form a planarized surface such that a top of the gate, tops of the first sidewalls, and a top of the dielectric layer over the mesa are on the same planarized surface, depositing metal on the planzarized surface, annealing to form the gate into a metal silicided gate, and etching to remove excess non-silicided metal.

Abstract: The interface resistance between the source/drain and gate of an HFET may be significantly reduced by engineering the bandgap of the 2DEG outside a gate region such that the charge density is substantially increased. The resistance may be further reduced by using an n+GaN Cap layer over the channel layer and barrier layer such that a horizontal surface of the barrier layer beyond the gate region is covered by the n+GaN Cap layer. This technique is applicable to depletion and enhancement mode HFETs.

Abstract: A method for fabricating a gate structure for a field effect transistor having a buffer layer on a substrate, a channel layer and a barrier layer over the channel layer includes forming a gate including silicon, forming first sidewalls of a first material on either side and adjacent to the gate, selectively etching into the buffer layer to form a mesa for the field effect transistor, depositing a material layer over the mesa, planarizing the material layer over the mesa to form a planarized surface such that a top of the gate, tops of the first sidewalls, and a top of the material layer over the mesa are on the same planarized surface, depositing metal on the planzarized surface, annealing to form the gate into a metal silicided gate, and etching to remove excess non-silicided metal.

Abstract: A method of fabricating a GaN HEMT includes growing a first epitaxial layer on a substrate, growing a second epitaxial layer on the first epitaxial layer, growing a third epitaxial layer on the second epitaxial layer, depositing a first dielectric film on the third epitaxial layer, using dielectric films to form a first sidewall dielectric spacer, forming a sidewall gate adjacent the first sidewall dielectric spacer. The sidewall gate may be made to be less than 50 nm in length.